Nitrogen Dioxide Comparison*
Nitrogen dioxide (NO2) is a reddish-brown gas
with a pungent odour and is partially responsible for the "brown haze" observed near large cities. The major sources of
oxides of nitrogen are automobiles and industrial facilities.
The five-year average (1998-2003) of NO2
concentrations showed that Edmonton and Calgary averaged 0.022 ppm and 0.023 ppm. Edmonton experienced no change in 2003,
while Calgary's concentration increased to 0.024 ppm. These values were somewhat higher than most of the Canadian cities
compared. Only Toronto and Hamilton had the same or higher concentration levels. The Alberta values were still
substantially lower than those in L.A. County (0.044 ppm) and New York City (0.032 ppm). Edmonton and Calgary both had
higher average concentrations than either Dallas or Seattle. Most cities used in the comparison either decreased or
remained at their previous levels in 2003. Calgary and Regina were the only cities in the comparison to experience an
increase in nitrogen dioxide concentrations in 2003 compared to their previous five-year averages.
|
Annual Average NO2
|
|
City/County
|
5 Year Average (1998-2003)
|
2003
|
|
Montreal
|
0.018
|
0.018
|
|
Ottawa
|
0.020
|
0.018
|
|
Toronto
|
0.024
|
0.022
|
|
Hamilton
|
0.022
|
0.021
|
|
Winnipeg
|
0.014
|
0.012
|
|
Regina
|
0.013
|
0.014
|
|
Edmonton
|
0.022
|
0.022
|
|
Calgary
|
0.023
|
0.024
|
|
Fort Saskatchewan
|
0.013
|
0.013
|
|
Fort McMurray
|
0.007
|
0.005
|
|
Greater Vancouver
|
0.018
|
0.018
|
|
L.A. County
|
0.044
|
0.035
|
|
New York
|
0.032
|
0.031
|
|
Dallas
|
0.017
|
0.015
|
|
Seattle
|
0.020
|
0.018
|
*The cities were compared by looking at the differences in their annual averages over a five-year period (1998-2003) and their most recent annual averages (2003). The city averages were calculated by finding the average of the annual average values for each station within a city. Each city did not necessarily have the same number of stations and it is important to note that this may affect exactly how representative an average is for a given city. Also, some stations may not have been operational for a majority of the time of the comparison, and therefore only stations that had data for at least four out of the five years were used. These same stations were also used in calculating the 2003 averages. The table below shows the number of stations that satisfied the criteria and were thus used for calculating the city averages.
|
City\County
|
# of Stations Used in Analysis
|
|
Montreal
|
12
|
|
Ottawa
|
2
|
|
Toronto
|
5
|
|
Hamilton
|
1
|
|
Winnipeg
|
2
|
|
Regina
|
1
|
|
Edmonton
|
3
|
|
Calgary
|
3
|
|
Fort Saskatchewan
|
1
|
|
Fort McMurray
|
2
|
|
Greater Vancouver
|
12
|
|
L.A. County
|
14
|
|
New York
|
5
|
|
Dallas
|
3
|
|
Seattle
|
1
|
|
